A roller which can be manufactured in accordance with the method of the present invention is shown in FIGS. 1 and 2 of DE-OS No. 3024537. The rolling body comprises a hub mounted on a ball bearing, a roller sleeve, and an annular portion arranged therebetween along the axial center of the rolling body. To increase the load capacity of the roller and to avoid tilting of the roller sleeve as a result of elastic deformation of the annular portion, circumferentially distributed reinforcing ribs are provided on both sides of the annuIar portion. These stellate, radially directed reinforcing ribs are integrally formed with the roller sleeve and the hub, as well as with the annular portion. When this known roller is manufactured by injection molding, undesirable problems arise with the homogeneity of the material of the finished roller on account of the complex form of the mold. Upon the meeting of two differently directed flows of plastic material, e.g. as a result of flow around a tool portion, a juncture is formed which causes a reduction in strength in that area of the roller and which forms a weak spot in the structure of the roller material. As a result the roller will fail prematurely under high loads or will be suitable for use only under small loads. This is particularly disadvantageous when the juncture is formed in the area of the roller sleeve, because this is the place at which the greatest bending strain is exerted and the area near a juncture is able to withstand only small stresses.